What do the dots mean on squash balls?

Related questions

1. Is squash a hard sport?
2. Is squash better than racquetball?
3. Is racquetball and squash the same thing?
4. What is squash drink called in America?
5. Is squash a real sport?
6. Who invented squash sport?
7. Which is better tennis or squash?
8. What's the difference between tennis and squash?
9. Why is squash the healthiest sport?
10. Can you play squash alone?

Tags

1. #between
2. #which
3. #black
4. #their
5. #double
6. #suitable
7. #bounce
8. #squash
9. #balls
10. #adults
11. #level
12. #determines
13. #always
14. #these
15. #called
16. #yellow
17. #difference
18. #coloured